1. Field of the Invention
The present invention relates to an air stream generating apparatus and, more particularly, to an air stream generating apparatus which increases air flow rate and wind pressure.
2. Description of the Prior Art
A conventional air stream generating apparatus will be described with an example used in an air cleaning apparatus with reference to FIG. 1. In FIG. 1, reference numeral 1 designates dust collecting electrode plates, which are arranged at a predetermined interval along an air flow passage. Ionizing wires 2 are respectively installed at the outside position isolated at a distance r from the line connecting the ends 1a of the respective electrode plates 1 on extension lines from substantially central positions of the gaps between the electrode plates 1. A predetermined high voltage of approx. 15 KV is applied to the electrode plates 1 as negative polarity between the ionizing wires 2 and the electrode plates 1 from a power source E. A corona discharge is produced between the wires 3 and the electrode plates 1 upon application of the voltage between wires 3 and the electrodes 1, thereby imparting kinetic energy to the viscous gas molecules to generate an air stream directed from the wires 2 toward the intervals when numerous positive ions are attracted to the side of the electrode plates 1. When the air stream is produced, dust particles in the air are charged with positive ions and are collected on the dust collecting electrode plates 1.
A force for producing an air stream in the interval when a voltage supplied from the power source E to between the wires 2 and the electrode plates 1 is constant, is, as shown in FIG. 1, given by the component force Fcos .theta. of the force F directed from the wire 3 to the electrode plate 1, where the .theta. is an opening angle from the line directed toward the central position of the gap from the wire 2 as an origin and the line for connecting the ends 1a of the electrode plates 1. When the distance r approaches to 0 in this case, the angle .theta. approaches 90.degree. and accordingly the force Fcos .theta. approaches 0. Thus, the force for producing the air stream is substantially vanished. When the distance r is, on the other hand, increased, an electric field between the wire 2 and the end 1a of the electrode plate decreases proportionally by 1/r.sup.2, thereby remarkably weakening the corona discharge. Thus, similarly to the above, the air stream is substantially vanished. In this manner, when the voltage supplied from the power source is constant, an adequate value exists in the set range of the distance r, thereby defining the velocity of the air stream to be produced substantially to a predetermined value of approx. 0.5 to 2 m/sec.
The volume and the cleaning efficiency of a cleaning chamber to be cleaned by an air cleaning apparatus are different depending upon the purpose for using the cleaning chamber. Thus, an air flow generating apparatus used in the air cleaning apparatus requires the performance capability of generating an air flow rate and an air pressure larger than the above-described values corresponding to them. The above-described example has been described with an example of the air flow generating apparatus used in the air cleaning apparatus. However, when this example is applied to an air conditioner (a room cooling and heating apparatus), the apparatus requires air flow velocity and air pressure (static and dynamic pressures) much larger than the value obtained in the conventional apparatus.
However, in the conventional air flow generating apparatus, there are disadvantages such that the velocity and air pressure of the air stream to be produced are defined substantially to a predetermined value which is slightly lower than the degree to be insufficient as desired when the high voltage of the power source is defined to a constant value.